Antimicrobial Metal Working Fluids

ABSTRACT

Aqueous alkaline metal working fluids and concentrates thereof and processes for their use are disclosed. Processes to reduce the presence of  Mycobacteria  in a metal working environment are also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 11/051,362, filedFeb. 4, 2005 (now allowed), which claims priority to U.S. ProvisionalApplication Ser. No. 60/542,672, filed Feb. 6, 2004, the entiredisclosures of which are incorporated herein by reference in theirentirety.

FIELD OF THE INVENTION

The present invention generally relates to metal working fluids andtheir uses. The present invention relates to aqueous alkaline metalworking fluids and concentrates thereof and processes for their usewhile diminishing the likelihood of microbial proliferation. In certainembodiments, the processes reduce the presence of Mycobacteria inaqueous alkaline metal working fluids or in a metal working environment.

BACKGROUND OF THE INVENTION

The increasing cost and disposal problems of non-aqueous, oil basedfunctional fluid compositions has accelerated the demand for aqueousbased functional fluid compositions. Aqueous based metalworking fluidshave been gaining in importance over non-aqueous metalworking fluidsbecause of their economic, environmental and safety advantages. Waterbased metalworking fluids have been used in chip forming and non-chipforming metalworking processes well known in the art such as drilling,tapping, broaching, grinding, rolling, drawing, spinning, milling,bending, turning and stamping.

Typically, metal working fluids are used in open systems and are exposedto bacteria and other microorganisms. It has been recognized thatcertain fast growing, easily recognizable bacteria affect fluidperformance in use or during extended storage. Use of antimicrobials inaqueous alkaline industrial fluids to reduce the deterioration of fluidperformance caused by microbial action on fluid components over time isknown in some circumstances.

Due to their comparatively slow growth, other, more resistant,microorganisms, such as Mycobacter have been the focus of less concern.One possible reason for this may be that significant deterioration andhence lowered performance of these industrial fluids by slow-growingorganisms is considered relatively unlikely. More recently, it has beenproposed that high levels of Mycobacter may be related to respiratoryhealth effects associated with occupational exposure to metal workingfluids, including occupational asthma, bronchitis, and hypersensitivitypneumonitis. Wallace, Jr., R. J. et al., “Presence of a Single Genotypeof the Newly Described Species Mycobacterium immunogenum in IndustrialMetalworking Fluids Associated with Hypersensitivity Pneumonitis”,Applied and Environmental Microbiology, Vol. 68, No. 11, p. 5580-5584,November 2002. Long periods of time between complete changes out ofsumps containing recirculating metal working fluids may lead to sizableMycobacter populations. Significant aerosol levels encountered incertain metal working environments tend to increase the potential forworker exposure.

In some situations, formalin or compounds evolving formalin orformaldehyde have been used to reduce bacterial populations. Elevatedworking temperatures experienced in some metal working processes maylead to substantial volatilization of formalin or formaldehyde orbreakdown of formalin precursors, requiring routine reintroduction ofthese compounds into the working fluid. In addition, in open systems,and in particular those systems that generate aerosols, such as metalworking environments, formalin raises its own environmental andhealth-related concerns for worker exposure. Another drawback of theseformaldehyde-related systems is that they appear ineffective againstopportunistic microorganisms such as Mycobacter.

A limited number of other antimicrobials such as chlorinated phenols,isothiazolinones and dicyclohexylamine have been found to have someefficacy against Mycobacteria in certain situations. Their utilizationin metal working fluid operations and environments is hampered bydrawbacks in the areas of worker safety, wastewater management, orstability. For example, chlorinated phenols are highly regulated by theEPA in waste streams. Isothiazolinones are expensive, sensitizing agentsto tissue, and are not stable in alkaline environments. Puredicyclohexylamine is toxic by ingestion and absorption and corrosive tothe respiratory system.

As a means of extending fluid life and performance, certain secondaryalkanolamines have been employed as antimicrobial agents to reducecomponent deterioration by Pseudomonas or Fusarium species. R. Skold andP. Raune, U.S. Pat. No. 5,633,222; L. Edebo and M. Sandin, U.S. Pat. No.5,132,046. Certain antimicrobial lubricants that include an alkyl etheramine component have found use in food or beverage container conveyorsystems. It has been proposed that these lubricants are useful inreducing slime formation caused by microbial action on food residues,thus improving conveyor performance. Hei, et al. U.S. Pat. No.5,683,874; Hei, et al. U.S. Pat. No. 5,723,418; and Hei et al. U.S. Pat.No. 5,932,526.

The extent of broad spectrum antimicrobial activity and the level ofefficacy for the general class of ether amines appear unpredictable.Hei, et al., U.S. Pat. No. 5,683,874, and Li, et al. U.S. Pat. No.6,214,777, each disclose lubricating compositions which may include anether amine for use in conveyor systems where external stresses, such asworking temperature or working pressure, are minimal. In Hei, et al.(‘874’), certain ether amines have ascertainable activity against somemicroorganisms under certain conditions. Under similar workingconditions Li et al. discloses certain ether amines at much increasedloadings which require a quaternary phosphonium compound as anantimicrobial to achieve the desired effect. External stresses such aselevated temperatures or pressures imposed by the working environment ofprocesses such as metal working may further impact efficacy of certainether amines through undesired thermal degradation, side reactions,volatilization, and the like. Under working conditions with increasedexternal stresses, it is difficult to predict whether certain etheramines would have broad spectrum activity, a more limited range ofactivity against some microorganisms, or no activity at all.

There is a need to provide new metal working fluids and methods of theiruse that inhibit microbial growth including Mycobacteria in metalworking fluids as well as metal working environments. There is also aneed to provide new metal working fluids that remain effective againstMycobacteria after exposure to workpiece-tool contact zone workingpressures of greater than about 60 psi or workpiece-tool contact zoneworking temperatures of greater than about 50° C. in metal workingfluids as well as metal working environments. The present invention isdirected to these and other important ends.

SUMMARY OF THE INVENTION

The present invention generally relates to metal working fluids andtheir uses. The present invention provides aqueous alkaline metalworking fluids and concentrates thereof and processes for their use. Insome embodiments, the metal working fluids of this invention inhibitgrowth of Mycobacteria or reduce the presence of Mycobacteria in a metalworking environment.

Mycobacteria, Mycobacter and Mycobacterium all refer to a genus ofrelatively slow-growing microorganisms that have a coating external totheir cell walls. These bacteria are often resistant to typicalbactericidal treatments used in metalworking fluid applications. Thelevel of these opportunistic microorganisms increase in both the workingfluids and the adjoining metal working environments with time, evenafter treatment with typical biocides. While not wishing to be held toany one theory, it is believed that Mycobacter are an opportunisticbacteria whose proliferation is suppressed while other more rapidgrowing species of bacteria such as Pseudomonas or fungi such asFusarium are present. Typical antimicrobial treatments of metal workingfluids reduce these more susceptible, rapid-growing species and allowMycobacter to proliferate due to their resistance to the typicalantimicrobials.

A workpiece-tool contact zone is the area where the tool and workpiecesurfaces are in contact with each other during the metal workingoperation and areas immediately adjacent thereto. Metal working fluidsare exposed to the greatest environmental stresses in the workpiece-toolcontact zone. In certain metal working fluid operations, such as forexample, cutting, shaping, molding extruding, pressing and the like, theinteraction of the metal being worked and the tool used to modify theworkpiece generates significant pressure or heat. Generally, thispressure or heat is referred to as working pressure or workingtemperature respectively. Working pressures and working temperatures arethe pressures and temperatures experienced by the metal surfaces and theaqueous alkaline metal working fluids at the contact zone during themetal working operation. Working temperatures in a workpiece-toolcontact zone range from about 50-1500° C. or more, typically involvingworking temperatures of 50, 100, 150, 200, 300, 500, 1000 or 1500° C.Working pressures in a workpiece-tool contact zone range from about60-10000 pounds per square inch (psi), typically involving contact zoneworking pressures of 60, 100, 500, 2000 or 10000 psi, or more. Thepresent invention provides utility and reusability in theseenvironments. Any additives to the working fluid must be able towithstand one or more of these extreme conditions and maintain theireffectiveness.

An aqueous alkaline metalworking fluid according to this invention mayoptionally contain various additives well known in the art such as forexample corrosion inhibitors, surfactants, emulsifiers, extreme pressureadditives, antifoam agents and antimisting agents. The compositions andusable concentrations of these additives are well known in the art andsuch compositions and concentrations may be optionally employed in thepractice of this invention. Any of the various additives may be employedin the invention provided that their use does not interfere with thedesired antimicrobial action.

In one embodiment, the invention is directed to aqueous alkaline metalworking fluids comprising from about 10 to about 20,000 ppm of at leastone alkyl ether amine having the formula Ia or Ib:

and an extreme-pressure additive. In any of the formula Ia or Ib alkylether amines, R₁ is independently C₂-C₁₈ alkyl. In certain otherpreferred embodiments, R₁ is independently C₂-C₁₀ alkyl. Alternatively,R₁ is independently C₈-C₁₀ alkyl, or R₁ is independently C₈-C₁₀ alkyl orC₁₂-C₁₄ alkyl. In other preferred embodiments, at least one R₁ is C₂-C₈alkyl. In formula Ia or Ib alkyl ether amines, R₂ and R₃ are eachindependently an alkylene having two to ten carbon atoms. Preferably,each R₂ and R₃ is independently C₂-C₄ alkylene. More preferably, atleast one of R₂ and R₃ is —CH₂CH₂CH₂—. Even more preferably each R₂ andR₃ is —CH₂CH₂CH₂—. In certain preferred embodiments, R₁ is independentlyC₂-C₁₀ alkyl and each R₂ and R₃ is independently C₂-C₄ alkylene. Evenmore preferably, the amine has the formula:

where R₁ is independently C₈-C₁₀ alkyl. In some preferred embodiments,the aqueous alkaline metal working fluids further comprise a workpiececorrosion inhibitor, a film forming additive, an antifoaming agent, or aless than detersive amount of surfactant.

Extreme pressure additives reduce tool wear while increasing work speed,thus making it possible to cut hard metals and increase productionrates. The three distinct varieties of extreme pressure additives arephosphate esters, active sulfur (polysulfides), and chlorinatedadditives. Typical examples of extreme pressure additives include butare not limited to phosphate esters such as polyoxyethylene oleyl etherphosphate and other phosphates; polysulfides having one or more reducedsulfur atoms capable of forming metal sulfide such as di-tert-dodecylpolysulfides and di-tert nonyl polysulfides; and chlorinated hydrocarbonadditives carbon based molecules with chlorine substituted forhydrogens, wherein the chlorine content in the molecule is usuallygreater than about 5% by weight. Chloroalkanes or chlorinated carboxylicacids, such as octadecanoic acid are typical examples of chlorinatedhydrocarbon extreme pressure additives.

Workpiece corrosion inhibitors are additives used in metal workingfluids to reduce the amount of corrosion caused by the presence of waterthat pools in depressions and imperfections of the workpiece or toolsurface. Any workpiece corrosion inhibitors known in the art aresuitable provided that they do not interfere with the desiredantimicrobial features of the invention. Examples of workpiece corrosioninhibitors are ethanolamine combined with boric acid, triazole compoundssuch as benzotriazole or tolytriazole, organic carboxylic acids having6-10 carbon atoms, or dicarboxylic acids having 10-14 carbon atoms, orany mixtures thereof.

Anti-foaming agents are additives used to reduce foaming in aqueousalkaline metal working fluids which may interfere with metal workingprocesses. Foaming is undesirable in metal working operations because itmay reduce cooling at the workpiece-tool contact zone and causesnumerous containment transport and control problems. Examples includesiloxane glycol copolymers, polyether modified polysiloxanes, reactionproducts of silicon dioxide and organosiloxanes, organosiloxanepolymers, hydrophobically treated silica or ethoxylated/propoxylatedhydrocarbons, or mixtures thereof.

The esters, fatty acids and oils in metal working fluids form films onthe surfaces of tools and work pieces that they contact during metalworking operations. The films are typically formed when the polarties ofthe esters, fatty acids and oils associate with the charges on the metalsurfaces. Any film forming additive is suitable so long as it does notinterfere with the stability, reusability or antimicrobial action of themetal working fluid. Mineral oils form a hydrodynamic boundary betweenthe tool and work piece. This film acts as a boundary to lubricate thetool and work piece contact zone.

A “detersive amount of surfactant” refers to an amount of surfactantrequired in a liquid to make it act as a detergent, that is toeffectively clean soils and oils from a surface. Surfactants alone arenot very efficient detergents, but act in combination with othercomponents in a cleaning liquid to provide a detergent action.Typically, an amount of a surfactant is added to a liquid as an aid oradjuvant to assist in providing detergent action. A detersive amount ofsurfactant depends on the presence of other components available to forma detergent. In some embodiments of the present invention the metalworking fluid comprises surfactant. This surfactant is provided inamounts that are less than detersive amounts due to the absence of othercomponents available in the metal working fluid to provide detergentaction. In the present invention, the surfactant is provided to adjustthe HLB “hydrophile/lipophile balance” and aid the dispersion of themetal working fluid concentrate in water. No detergent action isdesirable or provided. The removal of protective oils on a workpiece ina metal working environment is undesirable due to the flash rusting of aworkpieces within short periods of time in the absence of protectivecoatings. Also, a detersive amount of surfactant in aqueous alkalinefluids is likely to demonstrate a significant degree of foaming that isundesirable in operations involving metal working fluids. This foamingis exacerbated by the high pressure introduction of metal working fluidto the workpiece tool contact zone which causes turbulence resulting inincreased foaming. A “less than detersive amount of surfactant” in ametal working fluid does not increase the fluid's ability to clean soilsand oils from the workpiece or tool, or create significant levels offoaming.

In certain preferable embodiments, the aqueous alkaline metal workingfluids, after exposure to workpiece-tool contact zone workingtemperatures of greater than about 50° C. or working pressures ofgreater than about 60 psi, remain effective against growth ofMycobacteria. Working temperatures in a workpiece-tool contact zonerange from about 50-1500 ° C. or more. In some preferred embodiments themetal working fluids are exposed to working temperatures of 50, 100,150, 200, 300, 500, 1000 or 1500° C. in the workpiece-tool contact zone.Working pressures in a workpiece-tool contact zone range from about60-10,000 psi. In some preferred embodiments the metal working fluidsare exposed to working pressures of 60, 100, 500, 2000 or 10000 psi, ormore in the workpiece-tool contact zone.

In other preferred embodiments, the aqueous alkaline metal working fluidremains stable after exposure to workpiece-tool contact zone workingtemperatures. By stable, it is meant that the metal working fluids arereusable, that is they neither separate into layers in the sump norappreciably decompose at the workpiece-tool contact zone or in the sumpafter exposure to working temperatures in the workpiece-tool contactzone. Preferably the level of decomposition of the metal working fluidsis less than about 50%, more preferably less than about 40%, even morepreferably less than about 20%, still more preferably less than about10%, yet more preferably less than about 1%. Most preferably, the metalworking fluid is essentially unchanged after exposure to workpiece-toolcontact zone working temperatures.

Aqueous alkaline metal working fluids are subject to normal degradationover time such as from contact with local aqueous diluents or exposureto light or air. In addition, these fluids are often exposed to extremestresses such as elevated pressure or temperature, especially in theworkpiece-tool contact zone which may assist in the degradation of thefluid components. As a consequence, every aqueous alkaline metal workingfluid has a finite lifetime in use and must necessarily be replaced.Typically, this occurs by incrementally removing a small portion of thefluid from service and replacing this with an equivalent amount ofvirgin working fluid. Aqueous alkaline metal working fluids of thepresent invention behave similarly, and typically have comparablelifetimes to analogous working fluids that do not contain the etheramines of the invention.

In yet other embodiments, the invention is directed to processes forinhibiting microbial growth in aqueous alkaline metal working fluids.The processes comprise the incorporation of a Mycobacterium inhibitoryeffective amount of at least one amine of the above formula Ia or Ibalkyl ether amines, wherein R₁ is independently C₂-C₁₈ alkyl, and R₂ andR₃ are each independently an alkylene having two to ten carbon atoms,preferably C₂-C₄ alkylene, into aqueous alkaline metal working fluids.An “inhibitory effective amount” refers to an amount of at least oneamine compound of the present invention that may prevent, inhibit, ordiminish the rate of Mycobacter growth relative to its growth in theabsence of the claimed amine compound in an aqueous alkaline metalworking fluid or a metal working environment. Typical levels of amine inthe aqueous alkaline metal working fluid include but are not limited tofrom about 10 to about 20,000 ppm.

In certain preferred embodiments directed to processes for inhibitingmicrobial growth in aqueous alkaline metal working fluids each R₁ isindependently C₈-C₁₀ alkyl. More preferably, when each R₁ isindependently C₈-C₁₀ alkyl, each R₂ and R₃ is —CH₂CH₂CH₂—. In otherpreferred embodiments, each R₂ and R₃ is —CH₂CH₂CH₂—, or each R₁ isindependently C₈-C₁₀ or C₁₂-C₁₆ alkyl. More preferably, when each R₁ isindependently C₈-C₁₀ or C₁₂-C₁₆ alkyl, each R₂ and R₃ is —CH₂CH₂CH₂—. Inyet other preferred embodiments, at least one R₁ is C₂-C₈ alkyl.

The invention also provides processes for reducing the presence ofMycobacteria in aqueous alkaline metal working environments. In theseprocesses, the aqueous alkaline metal working fluids comprise theincorporation at least one of the above alkyl ether amines of formula Iaor Ib, wherein R₁ is independently C₂-C₁₈ alkyl, and R₂ and R₃ are eachindependently an alkylene having two to ten carbon atoms, preferablyC₂-C₄ alkylene, at a level sufficient to inhibit the proliferation ofMycobacteria in metal working environments. In certain preferredembodiments, each R₁ is independently C₈-C₁₀ alkyl. More preferably,when each R₁ is independently C₈-C₁₀ alkyl, each R₂ and R₃ is—CH₂CH₂CH₂—. In other preferred embodiments, each R₂ and R₃ is—CH₂CH₂CH₂—, or each R₁ is independently C₈-C₁₀ or C₁₂-C₁₆ alkyl. Morepreferably, when each R₁ is independently C₈-C₁₀ or C₁₂-C₁₆ alkyl, eachR₂ and R₃ is —CH₂CH₂CH₂—. In yet other preferred embodiments, at leastone R₁ is C₂-C₈ alkyl.

Typically, a metal working environment includes any airspace, liquid orsolid surface on or in reasonable proximity to the workpiece beingmodified, the tool modifying the workpiece or the sumps, pumps,reservoirs or other equipment used to move or circulate the metalworking fluid at the location where the metal working is taking place.Notably, such environments include those occupied by workers operatingmetal working machinery who may come into contact with microbiologicalagents such as Mycobacter.

The invention also provides aqueous alkaline metal working fluidscomprising: from about 10 to about 20,000 ppm of at least one alkylether amine having the formula Ia or Ib:

wherein each R₁ is independently C₂-C₁₈ alkyl and each R₂ and R₃ isindependently C₂-C₁₀ alkylene; which after exposure to workpiece-toolcontact zone working temperatures of greater than about 200° C. remaineffective against growth of Mycobacteria. Preferably, the aqueousalkaline metal working fluids remain stable after exposure toworkpiece-tool contact zone working temperatures. Working temperaturesin a workpiece-tool contact zone range from about 50-1500° C. or more.In some preferred embodiments the metal working fluids are exposed toworking temperatures of 50, 100, 150, 200, 300, 500, 1000 or 1500° C. inthe workpiece-tool contact zone. Working pressures in a workpiece-toolcontact zone range from about 60-10,000 psi. In some preferredembodiments the metal working fluids are exposed to working pressures of60, 100, 500, 2000 or 10000 psi, or more in the workpiece-tool contactzone.

The invention also provides aqueous alkaline metal working fluidscomprising at least one amine having the formula Ia or Ib:

in an amount effective to inhibit Mycobacterium growth; and anantifoaming agent.

In any of the formula Ia or Ib alkyl ether amines, R₁ is independentlyC₂-C₁₈ alkyl. In certain other preferred embodiments, R₁ isindependently C₂-C₁₀ alkyl. Alternatively, R₁ is independently C₈-C₁₀alkyl, or R₁ is independently C₈-C₁₀ alkyl or C₁₂-C₁₄ alkyl. In otherpreferred embodiments, at least one R₁ is C₂-C₈ alkyl. In formula Ia orIb alkyl ether amines, R₂ and R₃ are each independently an alkylenehaving two to ten carbon atoms. Preferably, each R₂ and R₃ isindependently C₂-C₄ alkylene. More preferably, at least one of R₂ and R₃is —CH₂CH₂CH₂—. Even more preferably each R₂ and R₃ is —CH₂CH₂CH₂—. Insome preferred embodiments, the aqueous alkaline metal working fluidsfurther comprise a workpiece corrosion inhibitor, a film formingadditive, an antifoaming agent, or a less than detersive amount ofsurfactant. In certain preferred embodiments, R₁ is independently C₂-C₁₀alkyl and each R₂ and R₃ is independently C₂-C₄ alkylene. Even morepreferably, the amine has the formula:

where R₁ is independently C₈-C₁₀ alkyl.

Some embodiments provide a metal working fluid concentrate comprising:at least one amine having the formula Ia or Ib:

whereineach R₁ is independently C₂-C₁₈ alkyl; and each R₂ and R₃ isindependently C₂-C₁₀ alkylene; and at least one of an extreme-pressureadditive, antifoaming agent, workpiece corrosion inhibitor orcombination thereof. These concentrates provide aqueous alkaline metalworking fluids that are effective in inhibiting Mycobacterium growthwhen diluted.

Aqueous alkaline metal working fluids of the invention have from about10 to about 20,000 ppm of at least one amine of formula Ia or Ib.Preferable aqueous alkaline metal working fluids have from about 3000 toabout 6000 ppm of the amine. More preferably, the aqueous alkaline metalworking fluid has about 3000 ppm of the amine. Metal working fluidconcentrates of the invention have levels of the required amine whichmay exceed 20,000 ppm. The level of amine in the concentrate depends onthe dilution factor necessary to convert the concentrates into aqueousalkaline metal working fluids. For example, if a concentrate requires adilution factor of 10, then the concentrate may contain from about 100to about 200,000 ppm of the amine of formula Ia or Ib. Similarly, aconcentrate requiring a dilution factor of 50 may contain from about 500to about 1,000,000 ppm of the amine. Aqueous alkaline metal workingfluids may comprise more than 20,000 ppm and their concentrates maycomprise proportionately more based on their dilution factors. Thesehigher levels of amine may be used but are not economically preferred.

As employed above and throughout the disclosure, the following terms,unless otherwise indicated, shall be understood to have the followingmeanings.

“Alkyl” refers to an optionally substituted, saturated straight,branched, or cyclic hydrocarbon having from about 1 to about 20 carbonatoms (and all combinations and subcombinations of ranges and specificnumbers of carbon atoms therein which do not adversely affect etheramine solubility in the metal working fluid or metal working fluidperformance. Preferably, the alkyl is a straight chain hydrocarbon.Alkyl groups include, but are not limited to, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, cyclopentyl, isopentyl,neopentyl, n-hexyl, isohexyl, cyclohexyl, cyclooctyl, 3-methylpentyl,2,2-dimethylbutyl, and 2,3-dimethylbutyl, 2-ethylhexyl, octyl, decyl,undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,heptadecyl, octadecyl, nonadecyl, and eicosyl.

“Alkylene” refers to a bivalent alkyl radical having the general formula—(CH₂)n-, where n is 2 to 10. Non-limiting examples include methylene,trimethylene, pentamethylene, and hexamethylene. Alkylene groups can besubstituted or unsubstituted. In some embodiments, n is preferably 2 to4. In some more preferable embodiments, n is 3. In other embodiments,the alkylene moiety has one or more alkyl branches. In these embodimentsthe sum of the number of carbon atoms in the alkylene and alkyl branchesis an integer in the range of 2 to 10.

When any variable occurs more than one time in any constituent or in anyformula, its definition in each occurrence is independent of itsdefinition at every other occurrence. Combinations of substituentsand/or variables are permissible only if such combinations result instable compounds.

It is believed the chemical formulas and names used herein correctly andaccurately reflect the underlying chemical compounds. However, thenature and value of the present invention does not depend upon thetheoretical correctness of these formulae, in whole or in part. Thus itis understood that the formulas used herein, as well as the chemicalnames attributed to the correspondingly indicated compounds, are notintended to limit the invention in any way.

Experimental Section Procedure

I. The Inoculant

A conventional aqueous semi-synthetic metal working fluid that had beenused in a metal working environment and had tested^(i) positive for thepresence of Mycobacteria was used to assess the inhibitory effect ofseveral additives for metal working fluid. The metal working fluid wasfirst cultured^(ii) on Lowenstein-Jensen agar slant resulting in thegrowth of cultures identified as Mycobacteria. The Mycobacteria cultureswere then used to inoculate an aqueous solution containing 5% freshsemi-synthetic metal working fluid via a standard technique using aninoculation loop. The inoculum in the metal working fluid solution wasallowed to grow to form a Mycobacteria-laden inoculant. A Mycobacteriaconcentration of at least approximately 10⁷ CFU/ml was confirmed byplating the Mycobacteria-laden inoculant on DIFCO Mycobacteria 7H11 agarplates prepared according to the manufacturer's directions. Confirmationof the Mycobacteria concentration was made based upon comparison of theplates to known industry standards. ^(i)Testing was performed by acommercial biological laboratory using methods known and consideredreliable in that industry for biological classification of bacteria. Anexample of such testing is the Ziehl-Neelsen Staining technique used toidentify Mycobacteria.^(ii)The Mycobacteria-containng metal workingfluid was cultured on a Lowenstein-Jensen agar slant by a commercialbiological laboratory using known techniques to promote the growth ofany viable Mycobacteria present in the metal working fluid.

II. The Test Solutions

One liter solutions were made for testing using 5% aqueous dilutions ofthe Examples having formulae as recited in Table I. Examples 1 and 2 arecompositions according to the invention. Comparative Example 1 is acomposition using dicyclohexylamine (DCHA).

A fourth example, Comparative Example 2, was formulated by making a 5%aqueous dilution of a commercially available metal cutting fluidcontaining DCHA and compounds thereof. Mycobacteria-laden inoculant (50ml) was added to each one liter test solution. The test solutions wereinoculated three times: at zero hours, at twenty-four hours and atforty-eight hours. The inoculated test solutions were plated^(iii) atone and twenty-four hours after the first and second inoculations of thetest solutions and at one hour after the third inoculation according tothe procedure outlined in Experimental Procedure Section I forconfirming Mycobacteria concentration. Observations of the plates werethen made three weeks after the last inoculation. The results are shownin Table II as powers of ten (e.g. 3 means 10³ colonies. ^(iii)Thebacteria plates were DIFCO Mycobacteria 7H11 agar prepared as theirdirections recommend.

TABLE I Comparative Component Ex. 1 Ex. 2 Ex. 1 CP300 20 20 20 DI water41 41.2 40 Diglycolamide 5375 9 9 9 Base G7 4 4 4 Addconate M 3.7 3.53.5 Lubrophos LB-400 2 2 2 CI-750 0.25 0.25 0.25 Isononanoic Acid 5.71.8 1.5 Ocenol HD 90/95 0.7 Genapol 0-200 3.4 2.3 PA-1618 6 DA-1214 6Dicyclohexylamine 6

TABLE II Time, in hours T = 1 T = 24 T = 25 T = 48 T = 49 (InoculationNo.)-(Time (1)-(1) (1)-(24) (2)-(1) (2)-(24) (3)-(1) of Plating afterInoculation) Example 1 0 0 0 0 4 Example 2 3 0 0 0 0 Comparative 4 0 0 03 Example 1 Comparative Ex. 2 3 0 4 0 5 Key All results are exponentsfor 10^(X) except for 0. 0 equals zero, meaning no growth. (1)-(1) isthe first inoculation plated after one hour. (1)-(24) is the firstinoculation plated after 24 hours. (2)-(1) is the second inoculationplated after one hour. (2)-(24) is second inoculation plated after 24hours. (3)-(1) is third inoculation plated after one hour.

The disclosures of each patent, patent application and publication citedor described in this document are hereby incorporated herein byreference, in their entirety.

Those skilled in the art will appreciate that numerous changes andmodifications can be made to the preferred embodiments of the inventionand that such changes and modifications can be made without departingfrom the spirit of the invention. It is, therefore, intended that theappended claims cover all such equivalent variations as fall within thetrue spirit and scope of the invention

1. A process for reducing the presence of Mycobacteria in an aqueousalkaline metal working environment, comprising providing to the metalworking environment an aqueous metal working fluid incorporating aMycobacterium inhibitory amount of at least one amine of formula Ia orIb:

wherein each R₁ is independently C₂-C₁₈ alkyl; and wherein each R₂ andR₃ is independently C₂-C₄ alkylene.
 2. The process according to claim 1wherein said aqueous metal working fluid further comprises a workpiececorrosion inhibitor.
 3. The process according to claim 2 wherein saidworkpiece corrosion inhibitor comprises ethanolamine combined with boricacid, a triazole compound, an organic carboxylic acid having 6-10 carbonatoms, a dicarboxylic acid having 10-14 carbon atoms, or any combinationthereof.
 4. The process according to claim 1 wherein said aqueous metalworking fluid comprises about 10 to about 10,000 ppm of said at leastone amine.
 5. The process according to claim 1 wherein said aqueousmetal working fluid comprises about 3,000 to about 6,000 ppm of said atleast one amine.
 6. The process according to claim 1 wherein saidaqueous metal working fluid comprises about 3,000 ppm of said at leastone amine.
 7. The process according to claim 1 wherein said aqueousmetal working fluid further comprises a film-forming additive, anantifoaming agent, or both.
 8. The process according to claim 1 whereinthe aqueous alkaline metal working fluid remains stable after exposureto workpiece-tool contact zone working temperatures.
 9. The processaccording to claim 1 wherein the aqueous alkaline metal working fluidremains effective against growth of Mycobacterium after exposure to aworkpiece-tool contact zone working pressure of greater than about 60psi.
 10. The process according to claim 1 wherein said aqueous metalworking fluid comprises at least about 41% to about 99% water.
 11. Aprocess for reducing the presence of Mycobacteria in an aqueous alkalinemetal working environment, comprising providing to the metal workingenvironment an aqueous metal working fluid incorporating a Mycobacteriuminhibitory amount of at least one amine of formula Ia or Ib:

wherein each R₁ is independently C₂-C₁₀ alkyl; and wherein each R₂ andR₃ is independently C₂-C₄ alkylene.
 12. The process according to claim11 wherein said aqueous metal working fluid further comprises aworkpiece corrosion inhibitor.
 13. The process according to claim 12wherein said workpiece corrosion inhibitor comprises ethanolaminecombined with boric acid, a triazole compound, an organic carboxylicacid having 6-10 carbon atoms, a dicarboxylic acid having 10-14 carbonatoms, or any combination thereof.
 14. The process according to claim 11wherein said aqueous metal working fluid comprises about 10 to about10,000 ppm of said at least one amine.
 15. The process according toclaim 11 wherein said aqueous metal working fluid comprises about 3,000to about 6,000 ppm of said at least one amine.
 16. The process accordingto claim 11 wherein said aqueous metal working fluid comprises about3,000 ppm of said at least one amine.
 17. The process according to claim11 wherein said aqueous metal working fluid further comprises afilm-forming additive, an antifoaming agent, or both.
 18. The processaccording to claim 11 wherein the aqueous alkaline metal working fluidremains stable after exposure to workpiece-tool contact zone workingtemperatures.
 19. The process according to claim 11 wherein the aqueousalkaline metal working fluid remains effective against growth ofMycobacterium after exposure to a workpiece-tool contact zone workingpressure of greater than about 60 psi.
 20. The process according toclaim 11 wherein said aqueous metal working fluid comprises at leastabout 41% to about 99% water.